From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4A75C3F2CD for ; Sun, 1 Mar 2020 18:12:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 80966246CD for ; Sun, 1 Mar 2020 18:12:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="RK2eyc23" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726525AbgCASMa (ORCPT ); Sun, 1 Mar 2020 13:12:30 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:43976 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725945AbgCASMa (ORCPT ); Sun, 1 Mar 2020 13:12:30 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 021IAAeN004208; Sun, 1 Mar 2020 18:12:27 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=content-type : mime-version : subject : from : in-reply-to : date : cc : content-transfer-encoding : message-id : references : to; s=corp-2020-01-29; bh=ZZxiB4h1tWL5VBvR0EDV07M8QDEq5UmjiwyyYe8MlTY=; b=RK2eyc239vOlPYGJ3aANZNmA4yeb0OrNFfjPLAZuXN//pDxWv9arQpQ9CmHwQx/Wi3Dt w2tUg54eZ9DgqNcC990PR7HHf+nvseypWmhNw0wht40IY3D3ldtf2Bb5VtJ9NFBSpzwG bSXZuBA5bRfkgd8hMx9ZD/2IPp+2fzAyAkOhR6CXtMPukow1bP3OkYgDginAmqnCgw/C 5r9gR1rLynfMm3fj2gZmaZyS7RX5NoE9XNgA5y9jm5Ge6g9u0nv0keEXoLChNBqx+Jtz PVDhf9hA4q4Id9TcI3lYi86inO7XNVLieAqxy0ho+tLawu8PMk5FhNvX5gfpSjqxtJjW dQ== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2120.oracle.com with ESMTP id 2yghn2r1kd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 01 Mar 2020 18:12:27 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 021ICRuo073095; Sun, 1 Mar 2020 18:12:27 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3030.oracle.com with ESMTP id 2yg1ef11eq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 01 Mar 2020 18:12:27 +0000 Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 021ICGv6007784; Sun, 1 Mar 2020 18:12:16 GMT Received: from anon-dhcp-153.1015granger.net (/68.61.232.219) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sun, 01 Mar 2020 10:12:15 -0800 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) Subject: Re: [PATCH v1 00/11] NFS/RDMA client side connection overhaul From: Chuck Lever In-Reply-To: <3a891d0c-3192-6445-c4df-3725335e9d95@talpey.com> Date: Sun, 1 Mar 2020 13:12:14 -0500 Cc: linux-rdma@vger.kernel.org, Linux NFS Mailing List Content-Transfer-Encoding: quoted-printable Message-Id: References: <20200221214906.2072.32572.stgit@manet.1015granger.net> <3a891d0c-3192-6445-c4df-3725335e9d95@talpey.com> To: Tom Talpey X-Mailer: Apple Mail (2.3445.104.11) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9547 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 suspectscore=0 spamscore=0 mlxlogscore=993 malwarescore=0 bulkscore=0 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003010143 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9547 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 phishscore=0 spamscore=0 impostorscore=0 mlxscore=0 adultscore=0 mlxlogscore=999 lowpriorityscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003010142 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org > On Mar 1, 2020, at 1:09 PM, Tom Talpey wrote: >=20 > On 2/21/2020 2:00 PM, Chuck Lever wrote: >> Howdy. >> I've had reports (and personal experience) where the Linux NFS/RDMA >> client waits for a very long time after a disruption of the network >> or NFS server. >> There is a disconnect time wait in the Connection Manager which >> blocks the RPC/RDMA transport from tearing down a connection for a >> few minutes when the remote cannot respond to DREQ messages. >=20 > This seems really unfortunate. Why such a long wait in the RDMA layer? > I can see a backoff, to prevent connection attempt flooding, but a > constant "few minute" pause is a very blunt instrument. The last clause here is the operative conundrum: "when the remote cannot respond". That should be pretty rare, but it's frequent enough to be bothersome in some environments. As to why the time wait is so long, I don't know the answer to that. >> An RPC/RDMA transport has only one slot for connection state, so the >> transport is prevented from establishing a fresh connection until >> the time wait completes. >> This patch series refactors the connection end point data structures >> to enable one active and multiple zombie connections. Now, while a >> defunct connection is waiting to die, it is separated from the >> transport, clearing the way for the immediate creation of a new >> connection. Clean-up of the old connection's data structures and >> resources then completes in the background. >=20 > This is a good idea in any case. It separates the layers, and leads > to better connection establishment throughput. >=20 > Does the RPCRDMA layer ensure it backs off, if connection retries > fail? Or are you depending on the NFS upper layer for this. There is a complicated back-off scheme that is modeled on the TCP connection back-off logic. > Tom. >=20 >> Well, that's the idea, anyway. Review and comments welcome. Hoping >> this can be merged in v5.7. >> --- >> Chuck Lever (11): >> xprtrdma: Invoke rpcrdma_ep_create() in the connect worker >> xprtrdma: Refactor frwr_init_mr() >> xprtrdma: Clean up the post_send path >> xprtrdma: Refactor rpcrdma_ep_connect() and = rpcrdma_ep_disconnect() >> xprtrdma: Allocate Protection Domain in rpcrdma_ep_create() >> xprtrdma: Invoke rpcrdma_ia_open in the connect worker >> xprtrdma: Remove rpcrdma_ia::ri_flags >> xprtrdma: Disconnect on flushed completion >> xprtrdma: Merge struct rpcrdma_ia into struct rpcrdma_ep >> xprtrdma: Extract sockaddr from struct rdma_cm_id >> xprtrdma: kmalloc rpcrdma_ep separate from rpcrdma_xprt >> include/trace/events/rpcrdma.h | 97 ++--- >> net/sunrpc/xprtrdma/backchannel.c | 8 >> net/sunrpc/xprtrdma/frwr_ops.c | 152 ++++---- >> net/sunrpc/xprtrdma/rpc_rdma.c | 32 +- >> net/sunrpc/xprtrdma/transport.c | 72 +--- >> net/sunrpc/xprtrdma/verbs.c | 681 = ++++++++++++++----------------------- >> net/sunrpc/xprtrdma/xprt_rdma.h | 89 ++--- >> 7 files changed, 445 insertions(+), 686 deletions(-) >> -- >> Chuck Lever -- Chuck Lever